Erigeron hartwegii Greene, Erythea 3: 21. 1895 (as hartwegi)

Leaves often mostly with 1-directional orientation to one side of stems; blades (30–)40–60 × 1–4 mm, apices usually acute, faces glabrate to sparsely strigose. Phyllaries 0.5–0.8 mm wide, margins usually thick or only with narrow scarious rims, midnerves usually not distinct and orange-resinous, abaxial faces glabrate to sparsely strigose, sometimes sparsely, obscurely glandular; inner phyllaries (4–)5–6 mm. Ray florets 26–50; corollas 8–13 mm. Disc corollas 4–5.5 mm.

Flowering Apr–Jul. Rocky sites, commonly along rivers, hills in oak or pine-oak woodlands; 100–600 m; Calif.

Among the varieties of Erigeron foliosus, var. hartwegii is the most distinct, morphologically and geographically, and might justifiably be treated at specific rank.